Intermediary proposal for Traffic Shaping Handler for V4.0.

Note there is still 2 options for Write due to a "bug" on IoEvent
executor.

- Option 1) Thread.sleep() but issue
- Option 2) Thread + LinkedList (to ensure order) but risk of memory
pressure

Include a proposal of Test for TrafficShaping in testsuite: warning long
time testing (about 120s globally !